Fuel cells are increasingly being investigated as a power source for electric vehicles and other applications. One such fuel cell is the PEM (i.e. Proton Exchange Membrane) fuel cell that includes a so-called “membrane-electrode-assembly” (MEA) comprising a thin, solid polymer membrane-electrolyte having a pair of electrodes (i.e., an anode and a cathode) on opposite faces of the membrane-electrolyte. The MEA is sandwiched between a pair of electrically conductive fluid distribution elements (i.e., bipolar plates) which serve as current collectors for the electrodes, and contain a so-called “flow field” which is an array of lands and grooves formed in the surface of the plate contacting the MEA. The lands conduct current from the electrodes, while the grooves between the lands serve to distribute the fuel cell's gaseous reactants evenly over the faces of the electrodes. Gas diffusion media, which are typically porous graphite/carbon paper, are positioned between each of the electrically conductive fluid distribution elements and the electrode faces of the MEA, to support the MEA where it confronts grooves in the flow field, and to conduct current therefrom to the adjacent lands.
The electrodes of the MEA generally include an electrochemically active region or area formed of electrochemically active material. In this regard, the electrochemically active areas of each electrode include catalyst-coated particles embedded in a polymer binder. This electrochemically active area, however, may include different particles that are either too active or lack a desirable activity during operation of the fuel cell. The activity or lack of activity may result in failure of the electrodes due to the development of pinholes, catalyst layer cracking, delamination, or a general degradation of the electrode. As such, it is desirable to have a MEA that includes electrodes where the electrochemical activity may be controlled which will assist in preventing the above drawbacks.